The objective of this project is research on and development of new mass spectral techniques in order provide new and/or more rapid solutions to problems involving (1) chemical structural determination, (2) complex mixture analysis and (3) measurement of trace components in biological systems. The utility and scope of these mass spectral methods are determined, and a comparison to other types of analysis, both new and established, is carried out. Fast atom bombardment mass spectrometry and combined liquid chromatography - mass spectrometry are the techniques of current interest. Fast atom bombardment mass spectrometry in both the positive and negative ion mode has been applied extensively to the rapid structure determination of base and sugar-modified nucleosides and synthetic nucleotides. A microscale desalting procedure to remove ionic contaminants which suppress sample ionization in fast atom bombardment mass spectrometry has been developed and applied to selected synthetic and biologically derived nucleosides. Studies of spectral anomalies generated by sample-matrix interactions during fast atom bombardment ionization continue.